It is clear that some chemicals can damage the health of animals and humans. (1) , this is not the only problem that (2) be caused by the careless use of chemicals. Chemicals can also (3) the ecological balance of the environment. If the ecological balance is disturbed, the results can be (4) serious.The (5) of DDT illustrates the problem. DDT, a chemical which kills insects, at first seemed to be a perfect answer (6) many problems. It would control insects that caused dangerous diseases, (7) insects that caused billions of dollars of damage to crops every year. Governments permitted and even (8) the use of DDT. Farmers in many countries (9) to spray it on their crops. The (10) results were good. Damage to crops (11) down, and profits went up. However, the chemical had effects which the scientists didn’t see in (12) . First, it also killed insects which were the (13) enemies of the harmful insects and which were therefore beneficial to farmers. Second, and perhaps worse, DDT did not kill (14) harmful insect. A few insects had natural resistance to the chemical. They (15) and reproduced in large numbers. In a few years there were large numbers of insects which were not (16) by DDT, and there were (17) insects which Could act as natural (18) on these new "super-insects". Finally, it became clear that DDT was not solving the insect problem. In fact, it was making the problem worse. It (19) became necessary to find a second (20) for the effects of the first.

A:Therefore B:However C:Meanwhile D:Besides

(It) is because she is (too) inexperienced (therefore) she does not know (how) to deal with the situation.（　）

A:It B:too C:therefore D:how

Smoking is considered dangerous to the health. Our tobacco--seller, Mr. Johnson, therefore, always asks his customers, if they are very young, whom the cigarettes are bought (51) . One day, a little girl whom he had never seen before walked (52) into his shop and demanded twenty cigarettes. She had the (53) amount of money in her hand and seemed very sure of herself. Mr. Johnson was so (54) by her confident manner that he (55) to ask his usual question. (56) , he asked her what kind of cigarettes she wanted. The girl replied (57) and handed him the money. While he was giving her the change, Mr. Johnson said laughingly that (58) she was so young she should (59) the packet in her pocket in case a policeman saw it. (60) , the little girl did not seem to find this very funny. Without (61) smiling she took the (62) and walked towards the door. Suddenly she stopped, turned (63) , and looked steadily at Mr. Johnson. There was a moment of silence and the tobacco-seller (64) what was going to say. All at once, in a clear, (65) voice, the girl declared, " My dad is a policeman," and with that she walked quickly out of the shop.

A:Therefore B:Instead C:Anyway D:Somehow

Smoking is considered dangerous to the health. Our tobacco--seller, Mr. Johnson, therefore, always asks his customers, if they are very young, whom the cigarettes are bought (51) . One day, a little girl whom he had never seen before walked (52) into his shop and demanded twenty cigarettes. She had the (53) amount of money in her hand and seemed very sure of herself. Mr. Johnson was so (54) by her confident manner that he (55) to ask his usual question. (56) , he asked her what kind of cigarettes she wanted. The girl replied (57) and handed him the money. While he was giving her the change, Mr. Johnson said laughingly that (58) she was so young she should (59) the packet in her pocket in case a policeman saw it. (60) , the little girl did not seem to find this very funny. Without (61) smiling she took the (62) and walked towards the door. Suddenly she stopped, turned (63) , and looked steadily at Mr. Johnson. There was a moment of silence and the tobacco-seller (64) what was going to say. All at once, in a clear, (65) voice, the girl declared, " My dad is a policeman," and with that she walked quickly out of the shop.

A:nevertheless B:moreover C:therefore D:then

Smoking is considered dangerous to the health. Our tobacco--seller, Mr. Johnson, therefore, always asks his customers, if they are very young, whom the cigarettes are bought (51) . One day, a little girl whom he had never seen before walked (52) into his shop and demanded twenty cigarettes. She had the (53) amount of money in her hand and seemed very sure of herself. Mr. Johnson was so (54) by her confident manner that he (55) to ask his usual question. (56) , he asked her what kind of cigarettes she wanted. The girl replied (57) and handed him the money. While he was giving her the change, Mr. Johnson said laughingly that (58) she was so young she should (59) the packet in her pocket in case a policeman saw it. (60) , the little girl did not seem to find this very funny. Without (61) smiling she took the (62) and walked towards the door. Suddenly she stopped, turned (63) , and looked steadily at Mr. Johnson. There was a moment of silence and the tobacco-seller (64) what was going to say. All at once, in a clear, (65) voice, the girl declared, " My dad is a policeman," and with that she walked quickly out of the shop.

A:Therefore B:Instead C:Anyway D:Somehow

? ?阅读下面的短文，文中有15处空白，每处空白给出4个选项，请根据短文的内容从4个选项中选择1个最佳答案。

A:nevertheless B:moreover C:therefore D:then

The "standard of living" of any country means the average person’s share of the goods and services the country produces. A country’s standard of living, (51) , depends first and (52) on its capacity to produce wealth. "Wealth" in this sense is not money, for we do not live on money (53) on things that money can buy: "goods" such as food and clothing, and "services" such as transport and "entertainment".
A country’s capacity to produce wealth depends upon many factors, most of (54) have an effect on one another. Wealth depends (55) a great extent upon a country’s natural resources. Some regions of the world are well supplied with coal and minerals, and have fertile soil and a favorable climate; other regions possess none of them.Next to natural resources (56) the ability to turn them to use. China is perhaps as well-off (57) the USA in natural resources, but suffered for many years from civil and external wars, and (58) this and other reasons was (59) to develop her resources. Sound and stable political conditions, and (60) from foreign invasions, enable a country to develop its natural resources peacefully and steadily, and to produce more wealth than another country equally well favoured by nature but less well ordered.A country’s standard of living does not only depend upon the wealth that is produced and consumed (61) its own borders, but also upon what is directly produced through international trade. (62) , Britain’s wealth in foodstuffs and other agricultural products would be much less if she had to depend only on (63) grown at home. Trade makes it possible for her surplus manufactured goods to be traded abroad for the agricultural products that would (64) be lacking. A country’s wealth is, therefore, much influenced by its manufacturing capacity, (65) that other countries can be found ready to accept its manufactures.

A:however B:furthermore C:similarly D:therefore

A Country’s Standard of Living The "standard of living" of any country means the average person’s share of the goods and services the country produces. A country’s standard of living, _____(51), depends on its capacity to produce wealth. "Wealth"_____(52) this sense is not money, for we do riot live on money_____(53) on things that money can buy: "goods" such as food and clothing, and "services" such as transport and entertainment. A country’s capacity to produce wealth depends upon many factors, most of_____(54) have an effect on one another. Wealth depends_____(55) a great extent upon a country’s natural resources. Some regions of the world are well supplied with coal and minerals, and have fertile (肥沃的) soil and a favorable climate; other regions possess none of them. Next to natural resources_____(56) the ability to turn them to use. China is perhaps as well-off_____(57) the USA in natural resources, but suffered for many years from civil and external wars, and_____(58) this and other reasons was_____(59) to develop her resources. Sound and stable political conditions, and_____(60) from foreign invasions, enable a country to develop its natural resources peacefully and steadily, and to produce more wealth than another country equally well favoured by nature but less well ordered. A country’s standard of living does not only depend upon the wealth that is produced and consumed_____(61) its own borders, but also upon what is directly produced through international trade._____(62), Britain’s wealth in foodstuffs and other agricultural products would be much less if she had to depend only on_____(63) grown at home. Trade makes it possible for her surplus (过剩的) manufactured goods to be traded abroad for the agricultural products that would_____(64) be lacking. A country’s wealth is, therefore, much_____(65) by its manufacturing capacity provided (如果) that other countries can be found ready to accept its manufactures.

A:otherwise B:certainly C:however D:therefore

It is clear that some chemicals can damage the health of animals and humans. (1) , this is not the only problem that (2) be caused by the careless use of chemicals. Chemicals can also (3) the ecological balance of the environment. If the ecological balance is disturbed, the results can be (4) serious.The (5) of DDT illustrates the problem. DDT, a chemical which kills insects, at first seemed to be a perfect answer (6) many problems. It would control insects that caused dangerous diseases, (7) insects that caused billions of dollars of damage to crops every year. Governments permitted and even (8) the use of DDT. Farmers in many countries (9) to spray it on their crops. The (10) results were good. Damage to crops (11) down, and profits went up. However, the chemical had effects which the scientists didn’t see in (12) . First, it also killed insects which were the (13) enemies of the harmful insects and which were therefore beneficial to farmers. Second, and perhaps worse, DDT did not kill (14) harmful insect. A few insects had natural resistance to the chemical. They (15) and reproduced in large numbers. In a few years there were large numbers of insects which were not (16) by DDT, and there were (17) insects which Could act as natural (18) on these new "super-insects". Finally, it became clear that DDT was not solving the insect problem. In fact, it was making the problem worse. It (19) became necessary to find a second (20) for the effects of the first.

A:Therefore B:However C:Meanwhile D:Besides